Vent, Valve & Volt
Weak airflow from vents, or one room hotter or colder than the rest

This one needs a licensed pro

Likely cause: the blower, coil or ductwork

Weak airflow everywhere with a clean filter and no ice points to the blower, a dirty coil, or duct problems. Call an HVAC technician.

Why this happens

Hoffmann Brothers lists the blower motor, closed dampers, leaky ducts and duct sizing after filters and grilles as causes of low airflow. The LibreTexts HVAC course adds undersized or poorly designed ducts. These need a technician to measure airflow and look inside the equipment.

What to do right now

  1. Keep the filter in place and the vents open.
  2. Leave the furnace or air handler panels closed.
  3. If the system makes new noises or smells, set the thermostat to Off until the technician comes.
  4. Note which rooms are weakest and when, to show the technician.

What to tell the HVAC technician

  • That airflow is weak at every vent with a clean filter and no ice.
  • Any new noises from the indoor unit.
  • Whether it got weaker suddenly or over time.
  • The brand and model of the furnace or air handler.

Build the full list: what to tell the HVAC technician.

Start this troubleshooter over

References (every fact above comes from one of these pages)
  1. Hoffmann Brothers: What triggers low airflow from AC vents
  2. LibreTexts (Coalinga College HVAC course): Common air distribution problems and solutions

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